1. Field of the Present Invention
The present invention relates to the inversion of allylic 1-hydroxy alcohols to allylic 3-hydroxy alcohols.
2. Description of the Prior Art
The present invention relates to the inversion of allylic 1-hydroxy alcohols of the structure R.sub.2 C.dbd.CR--CR.sub.2 OH where R is hydrogen or a suitable organic radical (e.g., substituted or unsubstituted alkyl, aryl, heterocyclic, etc.) capable of bonding to carbon to give the corresponding allylic 3-hydroxy alcohol of the structure R.sub.2 C(OH)CR.dbd.CR.sub.2. This inversion reaction will find utility in organic syntheses reactions in the agricultural chemical, pharmaceutical, and specialty chemical areas where such an inversion reaction (or transposition reaction) is needed.
In Tetrahedron Letters, No. 30, pp. 2621-2622 (1976) A. Yasuda et al. discuss a stereoselective 1,3-transposition reaction of allylic alcohols where an allylic 1-hydroxy alcohol, of the above-described general structure, is converted to the above-described allylic 3-hydroxy alcohol. The Yasuda et al. process involves the initial epoxidation of the allylic group of the allylic 1-hydroxy alcohol to form the corresponding epoxy compound, the subsequent formation of the epoxy mesylate therefrom, and the subsequent elimination of the epoxy mesylate (e.g., by reaction with sodium and liquid ammonia) to form the desired allylic 3-hydroxy alcohol. As used herein, the nomenclature "1", "2" and "3" in identifying the three carbon allylic configuration (C.dbd.C--C) is fixed in regard to allylic alcohols by having the alcoholic hydroxy group (--OH) on the "1" carbon atom. In such cases, the unsaturated carbon-to-carbon bond stretches from the "2" carbon atom to the "3" carbon atom.